The present invention is directed to a strapping machine having retained program timers. More particularly, the present invention is directed to a strapping machine that includes retained program timers in the event of cycle interruption.
Strapping machines are used in a wide variety of applications. In one such application, a strapping machine is incorporated into a stacker system that allows for the stacking of, for example, magazines and the like into a stack of such items for easy handling. A typical stacker conveys the material from a supply into a stacking path. The materials are then stacked onto a rigid element, such as a sized sheet of plywood and onto one another. The stacker assures alignment of the edges of the stacked materials to permit handling efficiency and to reduce the damage that could otherwise occur to the materials. The stacked materials are then compressed and a strap is applied around the materials to secure the stacked and bundled materials into a “log”.
The strapping machine is positioned along the length of the stacker at a location at which it is essentially a freestanding, fully independent component. In such an arrangement, the strapping machine is essentially integrated into the stacker for independent operation. In that stackers vary from one manufacturer to another, a variety of strapping machines and/or a single, versatile strapping machine must be configured for insertion into the stacker to integrate with the overall stacking and bundling operation.
In a typical arrangement, the stacker is configured having an elongated frame that can extend over twenty to thirty feet in length. The strapper is usually installed in the stacker frame near the mid-point of the frame. As such the strapper is not near to an end of the frame so that it is readily accessed. Rather, typically, access to the strapper requires that an operator walk around the rear of the machine to carry out any actions that are needed.
Operation of such a stacker/strapper machine is typically automatic with certain manual operator actions required. For example, the stacking of the product (e.g., magazines or more generally paper) is an automatic operation. The movement of the stack or bundle into the strapper is also an automatic operation. Likewise, the strapping and subsequent movement out of the strapper region is an automatic operation.
However, in order to reduce the potential for operator injury, there are various sensors located on the machine-that prevent operation or interrupt the strapping cycle in the event that an object passes through or beyond a barrier. These sensors are part of an interlock system that shuts down the strapper upon receipt of one or more signals. For example, in the event that an object enters the strapper region (e.g., near the strap chute), regardless of the point at which the cycle is, “breaking” the sensor path will generate a signal to stop the strapper. Even if it is in mid-cycle. However, in order to restart the strapper, a manual clearing and re-cycling of the strapping machine is required. This is so, even if the cycle was interrupted due to an inadvertent crossing of the sensor path.
While such interlocks provide a necessary and desirable safety enhancement, the inadvertent activation of the safety interlock system can result in unnecessary and costly equipment down time.
Accordingly, there exists a need for a strapping machine program that accommodates safety interlocks, but also reduces the amount of unnecessary equipment downtime. Desirably, such a system includes retained program timers to restart the strapping cycle at the point at which the cycle was interrupted.